With the known rotors of the type described above, there is a possibility, during use, of significant phase displacement between the vibration level of one blade and that of an adjacent blade, and of portions, separated from one another by said air gap, of the blades of each pair of adjacent blades nullifying said air gap and repeatedly colliding. The damping system mentioned above is arranged inside each chamber to frictionally cooperate with both portions of the closing wall of the relative chamber and to frictionally dampen said vibrations.
However, a drawback of the known rotors of the type described above is that the result described above is not always achieved since, in practice, it is not always possible to guarantee the concurrent contact between the damping system and both portions of the closing wall of the relative chamber.